In the operation of a gas turbine, it is desirable that the fuel present in the injectors be removed upon a sudden stop of the turbine. If the fuel were to be allowed to remain in the injectors, it would crack, i.e., form solid products, because of the high temperature present, and this would of course impair the operation of the injectors once the turbine is again started. One way of alleviating this problem is to inject the fuel in the injectors into the combustion chamber; however, this is not considered to be a desirable solution to the problem, since such injection of the fuel supplies considerable additional energy to the turbine which may cause it to overspeed. A further possible solution is to blow the oil out of the injectors into a drainage tank by means of compressed air, and the present invention is based upon this principle.
The concept of air injection in order to blow the fuel out of the injectors is known in the art and has been used in the past on injectors having a movable needle which acts as a stop valve and which is effective to close the injector nozzle when it is desired to stop the turbine, whereafter compressed air can be supplied to the injectors for cleaning. This principle is not, however, applicable to injectors that do not have a movable needle.